Many industrial processes are accomplished within a furnace, e.g., processes that require temperatures of at least about 200.degree. C., typically at least 1500.degree. C. for a high temperature furnace. In some furnace processes, such as chemical vapor deposition or semiconductor crystal growing using the Czochralski method, temperature uniformity must be carefully controlled simultaneously with high temperature heat transfer.
Graphite elements are sometimes used in these furnaces. For example, in semiconductor crystal growing applications, a graphite cup may support the melt container, and a cylindrical graphite "picket fence" heating element is the heat source. Precise and complex shapes of the graphite furnace elements may be required to accomplish their structural and thermal functions.
Because of the brittle nature and low strength of prior graphite materials used to construct furnace elements, graphite furnace elements were typically fabricated and shaped by machining from blocks of graphite. For cylindrical or cup-like shapes, this required the removal of significant amounts of graphite. Because of the amount of material removed, graphite machining is a long, slow, and expensive process.